I agree. We need to automate the process of notifying users that another reply has happened. This feature was sunsetted because of GDPR. See this article: https://www.hubspot.com/product-updates/sunsetting-the-ability-to-subscribe-to-follow-up-blog-comments
Now that GDPR is in place and fully functional, it is time for Hubspot to bring this feature back. If the portal has GDPR turned on then it should just apply the GDPR rules.
- Dave Orecchio